Teething - is this normal?

Sophie (18 weeks) has been having a couple of difficult teething days this week. She's been chewing her bib like mad this afternoon and when I went to take it off I noticed there was a little bit of blood on it. It was only a speck, and it was mixed with saliva (lovely). I've had a look in her mouth and can't see where it came from. She's also not bleeding from anywhere else, so it must have come from her mouth.

I feel like a bit of an idiot ringing the GP about a tiny bit of blood, but before I do is this normal with teething?